Circuit-breaker.



K. KUHLMANN.

GIRUUIT BREAKER.

APPLICATION FILED AUG. 16,1907.

Patented Apr. 20, 1909.

Inventor Karl KuhZma/m.

UNITED STATES PATENT ()FFIQE.

KARL KUHLMANN, OF BERLIN-PANKOW, GERMANY, ASSIGNOR TO GENERAL ELECTRICrent which but as heretofore applied to circuit controlif the currentexceeds the normal but only a ,which the tripping means can a COMPANY,A'OORPORATION OF NEW YORK.

CIRCUIT-BRIE AKER.

No. 918,681. Specification of Letters Patent. I

Patented April 20, 1909. Application filed August 16, 1907. Serial No.388,849.

with a predetermined time la to variations of current in the circuit,and this controlling member is normally locked in an inoperativeposition by a device which permits said memer to' control the circuitonly duringthe time the currentin the circuit is in excess of apredetermined limit. The restraining device is preferably controlled byan electromagnet or similar arrangement which will respond more quicklythan the controlling member to the current in the circuit so that whilethe current is abnormal the restraint upon the controlling member isremoved and the controlling member is free to control the circuit. Inthe preferred form of my invention the circuit-controller has a time lagsecured by means of a thermostatic device connected in the circuit, andthe time lag is altered in accordance with the amount and duration ofcurrent flowing for a short time rior to the o oration of the circuitcontroller .y causing tie movements of the thermostatic device inresponse to said current to store energy by any suitable means, and bycausing the stored energy to affect the encuit controller the instantthe current in the circuit becomes abnormal. form of energy storingdevice consists of a spring interposed between the thermostaticactuating device and the circuit controller and which is not strongenough to move the circuit controller unless the restraining device isrendered ineffective by abnormal current.

My invention will best be understood in connection with the accompanyingdrawing which is merely an illustration of one form in which myinvention may be embodied, and in which Figure 1 shows a thermostaticrelay as it ilppe'ars when thecurrent is normal; Fig. 2 t e mal and Fig.3 a similar device in which the thermostat is replaced by a form ofactuating device responsive to alternating current.

In the arrangement shown in the drawing the leads of the main circuit tobe controlled are marked 1 and 2, and a circuit-breaker 3 interposed inone of the leads enables the circuit to be opened. The circuit-breaker 3may be of any desired form and'may be tripped in any well-known manner,but the arrangement which I have shown comprises To all whom it mayconcern:

Be it known that I, KARL KUHLMANN, a i subject of the Emperor ofGermany, residin at Berlin-Pankow, Germany, have invente certain new anduseful Improvements in Circuit-Breakers; of which the following is aspecification. This invention relates to circuit controlling devices andmore particularly to automatic devices actuated only by an abnormalcurpersists for a predetermined length of time.

A thermostatic device such as a hot wire connected in the circuit is asimple and effective means for securing a time. lag in the operation ofan automatic circuit controller and is unaffected by changes in thefre-' quency or in the wave form of the current,

lers the circuit could not be closed until the thermostatic device hadcooled down to its normal tem erature. Difliculties were'also encounterewhere a circuit must be opened small amount, since a thermostatic devicewhen heated expands rapidly at first and continues to expand at aconstantly decreas ing rate, so that it reaches its complete elongationonly after a very considerable length of time. If the thermostat isarranged so that its ra id expansion tri s the circuitbreakerwit in areasonable ength of time when a current 10 per cent. greater than thenormal flows in the circuit, a long continued current very slightlygreater than normal will in time cause the thermostatic device to expandenough to trip the breaker. he object of my invention is to provide asimple and effective circuit-controlling device which will have a timelag and which can be reset immediately after trip ing; in flhct thebreaker only during the time the current exceeds a predetermined limit;in which the time lag of the circuit controlling device depends on thevamount and duration of the current flowing in the circuit for a shorttime prior to the operation of said device, and in general to improvethe construction and o eration of thermostatic tripping devices orcircuit-breakers.

In cangyin out my invention a controllin member or tie circuit isarranged to respon' The preferred a trip cil4 connected to the leads 1and 2 .by. means of trip circuit leads 5 and 6, by means of which thecircuit through the tri coil 4 may be closed to cause thecircuitreakerto open. v

My invention is shown in the drawings as embodied in a relay mountedupon a baseplate 7 of any suitable material and controling the circuitthrough the trip coil 4 of the breaker 3, although if the relay weremade large enough it could be used to control the circuitdirectly. Onelead 5 of the trip circuit is connected to a fixed contact 8 of therelay, while the other lead 6 of the tri circuit is connected to acircuit control er or movable contact arm 9 pivotally mounted drawing asa spiral spring 11 with one end connected to the contact arm 9 and theother end connected to an operating arm 12 mounted upon the pin 10 andhaving its free end in engagement with an actuating mechanism having atime lag and responsive to current in the main circuit. 'The mechanismas shown is a thermostatic device or strip 13 supported at each end byposts '14 carried on the base-plate 7. The thermostatic strip 13 isconnected in series with the circuit to be controlled and the operatingarm 12, the movable contact 9 and the strip 13 form in effect acontrolling member for the circuit or, in conjunction with the coil 4, atripping means movable with a predetermined .time lag in response tovariations of current for the purpose of controlling the circuit.

The position of the movable contact arm 9 is determined by a restrainingmeans or stop 'sufiiciently powerful to hold it immovable against theaction of the thermostatic strip 13. The restrainin means may be of anysuitable kind, but t e preferred form which I have shown consists of thesolenoid 15 having a core 16 forengaging the contact arm 9 to act as astop for said arm. The

core 16 is normally held in the position shown in Fig. 1 to lock the arm9 immovable by means of a spring 17 powerful enough to overcome thespring 11 and hold the contact arm 9 stationary regardless of theposition of the strip 13. The solenoid 15 is connected in series withthe circuit to be controlled and is so proportioned that when thecurrent in the circuit reaches a predetermined limit the core 16 isdrawn out of engagement with the contact arm 9, which is thereupon leftfree to move under the influence of the strip 13 and the energy storingdevice 11. The tension of the spring 17 may be varied to alter theamount of current at which the contact arm 9 is released by means of acalibrating eraser screw 18 mounted in a suitable support on thebase-plate 7.

Various types of actuating mechanism may be substituted for thethermostatic strip 13 and one of such mechanisms which I may use foralternating currents isshown in Fig. 3. This mechanism comprises a disk19 connected to the contact arm 9 through a spring 11 and provided witha short circuited coil 20 which as shown in Fig. 3 is normally partlybetween the poles of a magnet 21 having U-sha 'ed oles, one on each sideof the disk, an a with its winding connected in series with the circuitto be controlled;

The time lag of the circuit controlling device depends u on the rate ofexpansion of the strip13. if a current great enough to withdraw the core16 suddenly flows in the circuit, the time which ela see before the tripcircuit is closed depen s entirely upon the amountof current, as thestrip can expand and move the arm 9 unhindered anchat a rate determinedby the amount of the current. If a current slightly greater than normal,butnot great enough to withdraw the stop, flows for some time, the strip13 bows up a certain extent in response to said current, thereby storingenergy in the spring 11. I If the core is withdrawn while the strip 13is bowed, the arm 9. moves quickly to a point where the stored energy ofthe spring 11 is exhausted, and the timelag of the device under thesecircumstances depends on the time required for the arm 9 to move on fromsaid point into engagement with the fixed contact .8. 'This timeevidently de ends upon the positionof the point to whic 'the arm ismoved by the spring, which in turn depends upon the extent to which thestrip 13 was bowed by the slight abnormal current. The time lag of thedevice, therefore, varies with the amount and duration of-currentflowing for a short time preceding the withdrawal of the core 16.

The operation of the device is as follows: When the current is normal,the parts are in the position shown in Fig. 1; if the current increasesvery slightly above normal. the strip 13 begins to bow up into the formshown in Fig. 2 and in so doing moves the operating arm 12 about thepivot 10 thereby'straining the spring 11 f and storing energy therein.This movement has no eifect on the contact arm 9 which is held immovableby the core 16 of the solenoid 15. As /the current conv tinues toincrease a point is reached at which extent to which the strip 13 hadbowed up before the stop was removed, and from that point on until thecontact arm 9 engages the fixed contact 8 the rate of movement of thecontact armis determined-by-the rate of expansion of the strip 13. Ifthe'current drops down to normal before the contact arm 9 reaches thefixed contact 8, thesolenoid 15 releases the core 16, which is thenforced out by the spring 17 and forcibly returns the contact arm 9, toits normal inoperative position. If the contact arm 9 moves intoengagement with the fixed contact 8, the circuit through the trip coil 4is closed and the maincircuit is opened. The

instant the current in the main circuit ceases.

tothe form shown but intend to cover by the 2 5 appended claims allchanges and modifications which are-within the spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:-

1. In a circuit controlling device, the combination with a controllingmember movable with a time. lag in response to variations of current tocontrol the circuit, of a restraining device for preventing movement ofsaid controlling member when said device is in normal position and meansresponsive to abnormal current of predetermined amount whereby saiddevice is moved from normal position and said member is released fromrestraint during abnormal current.

2. In a circuit controlling device, the combination with a controllingmember movable with a time lag in response to variations of current tocontrol the circuit and capable of being forcibly moved to inoperativeposition, of means for forcibly movin said member to ino erativeposition when t e current is normai and actuated by abnormal current torelease said member. I

3. In a circuit controlling device, the combination with a controllingmember movable with a time lag in response to variations of current tocontrol the circuit and capable of being forcibly moved to inoperativeposition, of a spring-pressed member .for forcibly moving said member toinoperative position, and electromagnetic means responsive to currentfor controlling said member.

4. The combination with a circuit controller, of actuating means forsaid controller responsive with a time lag to abnormal current in thecircuit, a restraining member for normally reventing actuation of saidcontroller an means responsive to abnormal current of predeterminedamount whereby saidimember is moved into ineffective position and saidcontroller'is left free "to be actuated during abnormal current.

5. In a. circuit-breaker, the combination with tri ping means responsivewith a time lag to a normal current-in the circuit, of re strainingmeans for normally holding said tripping means in inoperative position,said restraining means being adapted to release the trippingv means uponthe occurrence of abnormal current of predetermined amount.

6. In a circuit-breaker, the combination with tri ping means responsiveWith a time lag to a normal current in the circuit, of a stop fornormally preventing the tripping of said circuit breaker, means formoving said stop to release said tripping means during abnormal currentof predetermined amount, and means for varying the amount of currentrequired to move said stop.

7. In a circuit-breaker, the combination with a controlling member, ofactuating means for said member responsive with a predetermined time lagto abnormal current in the circuit and capable of being forciblyreturned to inoperative position, and restraining means capable offorcibly returningsaid actuating means to inoperative position actuatedby abnormal current of predetermined amount to release said actuatingmeans.

8. The combination with a circuit-breaker of tripping means responsiveto abnormal current and requiring a predetermined time to move fromnormal to operative position, a stop for holding the tripping means innormal position, and means responsive to abnormal current ofpredetermined amount for moving the sto to release the tripping means.

9. T e combination with a circuit-breaker, of tripping means responsiveto abnormal current and requirin a predetermined time to move from normato operativeposition, a stop for holding the trippmg means in normalposition, releasing mean'sresponsive to current of predetermined amountfor movin the stop to release the tripping means, an

means for varying the relation of said releasing means to the sto 1,0.The combination with a circuit controlling member, of actuatingmechanism for moving said member with a time lag in response tovariations of current to control the circuit, a connection forpermitting said.

mechanism and said member to move independently of each other to aredeterr'nined extent, and restraining means ior holding said 'meinberimmovable when the current is norma 11. The combination with a circuitcontrolling member, of actuating mechanism for moving said member with atime lag in response to variation of current to control the c1rcuit, anenergy storing connection between said mechanism and said member, andrestraining means for holding said member immovable when the current isnormal.

12. The combination with a circuit controlling member, of actuatingmechanism for 5 mo-said member with a time lag in, re-

sponse to variation of current to -control the circuit, a resilientconnection between said mechanism and said member, a stop for holdingsaid member immovable, and means responsive to abnormal current formoving said sto to release the member.

13-. T e combination with a circuit con eraser ber ino erative when thecurrent is normal;-

' M. he combination with a circuit controlling member, of actuatingmechanism for moving said member with a time lag in response tovariation of current to control the circuit, energy'storing means foroperating said member arranged to receive energy from said actuatingmechanism, and restraining means for holding said member immovable whilethe current is normal. g

In witness whereof, I have hereunto set my hand this 29th day of July,1907. i

' KARL KUHLMANN.

Witnesses: Y

JULrIis' RUMLAND, (lsnan SINGER.

